Fast and efficient programming + testing of devboards is essential to keeping quality high and prices low. We’ve been happy with this ‘style’ of standalone ARM Cortex tester. We use a Teensy 3.6 as the brains since it has USB host for testing the USB enumeration, and an SD card that can hold the testing and shipping firmware hex files. The programming itself uses Adafruit_DAP to perform the Cortex SWD programming procedure https://github.com/adafruit/Adafruit_DAP. a pogo pin bed allows us to quickly program and test all the IO. The only special thing on this one is due to the 0402 5.1k CC resistors – we want to verify they aren’t tombstoned so we have a little circuitry to check that the pulldowns exist by enabling a pullup and then checking the analog voltage. this setup should be about 10 seconds-per-board cycle time.
What a cutie pie! Or is it… a QT Py? This diminutive dev board comes with our favorite lil chip, the SAMD21 (as made famous in our GEMMA M0 and Trinket M0 boards).
OLEDs! Inertial Measurement Units! Sensors a-plenty. All plug-and-play thanks to the innovative chainable design: SparkFun Qwiic-compatible STEMMA QT connectors for the I2C bus so you don’t even need to solder! Just plug in a compatible cable and attach it to your MCU of choice, and you’re ready to load up some software and measure some light.
Pinout and shape is Seeed Xiao compatible, with castellated pads so you can solder it flat to a PCB. In addition to the QT connector, we also added an RGB NeoPixel (with controllable power pin to allow for ultra-low-power usage), and a reset button (great for restarting your program, or entering the bootloader)
Runs Arduino like a dream, and can be used for basic CircuitPython projects. For more advanced usage like datalogging or fire storage, solder an SOIC SPI flash chip onto the bottom pads:
- Same size, form-factor, and pin-out as Seeed Xiao
- ATSAMD21E18 32-bit Cortex M0+ – 48 MHz 32 bit processor with 256KB Flash and 32 KB RAM
- Native USB supported by every OS – can be used in Arduino or CircuitPython as USB serial console, MIDI, Keyboard/Mouse HID, even a little disk drive for storing Python scripts.
- Can be used with Arduino IDE or CircuitPython
- Built in RGB NeoPixel LED
11 GPIO pins:
- True analog output on one I/O pin – can be used to play 10-bit quality audio clips in Arduino (CircuitPython does not have storage for audio clips)
- 9 x 12-bit analog inputs (SDA/SCL do not have analog inputs)
- 1 x Optional AREF on A1
- 9 x PWM outputs (A0 is analog out, A1 is not PWM capable)
- Hardware I2C port with STEMMA QT plug-n-play connector
- Hardware UART
- Hardware SPI
- Hardware I2S
- 6 x Capacitive Touch with no additional components required
- 3.3V regulator with 600mA peak output
- Optional SOIC-8 SPI Flash chip on bottom
- Reset switch for starting your project code over or entering bootloader mode
- USB Type C connector
- Really really small